1. Field of the Invention
The present invention relates generally to electric motors, and particularly to linear induction motors.
2. Technical Background
Electric motors have long been used in a host of industrial applications. Typically, an electric motor includes a rotor and a stator. The rotor essentially is a movable stage that includes a series of permanent magnets that are free to move with the stage. The stator includes a series of armature windings, or coils, mounted to a stationary base plate. This arrangement can be reversed such that the permanent magnets are stationary, with the coils mounted on the stator. In either case, the stage is propelled in the desired direction by energizing the coils. Depending on the application and/or design, either DC or AC electricity may be applied. The coils produce a magnetic flux when electrically energized. The interaction of the permanent magnets with the magnetic flux generated by the coils produces electromagnetic forces commonly referred to as Lorentz forces. The mass of the rotor spins inside a circular stator in response to these electromagnetic forces. Thus, electric motors convert electrical energy into rotating kinetic energy. By the nature of their design, these motors transfer the rotating kinetic energy externally through a rotating shaft connected to the center of the rotor.
The aforementioned approach has several drawbacks. Because magnets are employed in the rotor, the motor is typically very heavy. This also results in high-inertia low-torque motors. What is needed is a new type of stationary electric motor that offers the advantages of mechanical simplicity, light weight, high speed and power, with increased efficiency at high speed. What is also desirable is a motor that applies rotational kinetic energy to a rail surrounding a central void, or encircling the device itself, instead of merely spinning a shaft connected to the center of a rotor.